This invention relates to the casting art and is directed more particularly to a method of casting the metal body having more and more apertures therein.
A particular example of the type of casting with which the invention is concerned is a gas turbine blade of the air-cooled type. Such blades are usually hollow and include hundreds of cooling apertures.
The apertures in the hollow turbine blade may be made by a number of methods which include mechanical drilling, electrical disintegrating drilling or by casting the blade with metal wires in place. In the latter method the wires are removed by heating the casting in an atmospheric furnace at a temperature high enough to cause the wires to be removed by sublimation. The first two methods are obviously time-consuming and very expensive. Thus, in the latter method, the use for a period of time of an expensive item of equipment, namely the furnace, is required to carry out the sublimation.